Unloader assembly

ABSTRACT

An improved apparatus for operating on sheets of material includes an unloader assembly which engages a sheet of material and removes it from a punch press. Interconnected controls for both the punch press and unloader automatically initiate an unloading cycle upon completion of a punching cycle. Upon initiation of an unloading cycle, a clamp mounted on an unloader trolley is moved into gripping engagement with a leading end portion of the sheet. The trolley is then moved away from the punch press along a path extending over the pile on which the sheet is to be deposited. When the trailing end portion of the sheet has cleared the punch press, the trolley is stopped and the clamp is opened to release the sheet. To prevent interference between the pile of sheets and the trolley, the pile is disposed on a support table which is lowered whenever a detector assembly on the trolley detects that the pile extends above a predetermined height.

United States Patent 1 Linkus 1 July 24, 1973 UNLOADER ASSEMBLY [57] ABSTRACT [75] Inventor: Joseph A. Llnltus, Levittown, Pa,

[73] Assignee: The Warner & Swasey Company, An improved apparatus for operating on sheets of macleveland, i t elt ns yi sssn @25 9?! 5 9 1913 which 2 12 5 a sheet of material and removes itTroni apunc h press. Ih- [22] Ffled: 1971 terconnected controls for both the punch press and un- [21] Appl. No.: 133,873 loader automatically initiate an unloading cycle upon completion of a punching cycle. Upon initiation of an unloading cycle, a clamp mounted on an unloader trol- [52] U.S. Cl. 271/85, 271/88 ley is moved into gripping engagement with a leading [51] III. C B65]! 29/10 end portion of the sheet h trolley is then moved [58] Field Of Search ,.27l/8485, 88; 214/6 DK away from the punch press along a path extending over the pile on which the sheet is to be deposited. When the trailing end portion of the sheet has cleared the punch [56] References C'ted press, the trolley is stopped and the clamp is opened to UNITED STATES PATENTS release the sheet. To prevent interference between the 925,890 6/1909 Ferry 271/85 pile of Sheets and the trolley, the pile is disposed on a 2,262,236 11/1941 Huck 271/88 support table which is lowered whenever a detector as- 3,334,395 8/1967 ani 271/38 X sembly on the trolley detects that the pile extends Heide a above a predetermined 3,630,517 l2/l97l Enskat 271/88 Primary Examintzr-l idwardA Sroka Airway-Yam & Tarolli 13 Claims, 10 Drawing Figures PAIENTEU JUL 2 41973 SHEEI 2 0F 5 m/vsuroe L M/KUS JOSEPH A BY W 1477'0EN UNLOAIDER ASSEMBLY This invention relates generally to an apparatus for operating on sheet material and more particularly to an apparatus in which sheet material is removed from a machine by an unloader assembly.

Sheet material has heretofore been unloaded from punch presses and other machines manually or by means of an unloader assembly, such as the one shown in US. Pat. No. 3,358,853 to Thomas et al. Although unloader assemblies similar to the one disclosed in the aforementioned Thomas patent facilitate the unloading of a punch press or other machine, the speed with which the punch press and unloader assembly can process a sheet is somewhat impaired by the fact that an unloading cycle is initiated manually by the press operator at the end of an operating cycle. During operation of a known unloader assembly, the sheets are moved by feed rolls to a drop bay stacker which drops the sheets onto a pile. Of course, the inclusion of the stacker contributes to the cost of manufacturing this known unloader assembly.

The present invention provides an improved unloader which is automatically activated by controls for an associated punch press or other machine at the end of an operating cycle of the machine. By providing this cooperation between the unloader and machine controls, each sheet is removed from the machine by the unloader as soon as possible after completion of a machine cycle. During operation of the unloader, a sheet is pulled from the machine by a trolley which moves along a path extending over a pile of previously processed sheets. As sheets accumulate on the pile, the pile is automatically lowered to prevent interference between the pile and the trolley.

Accordingly, it is an object of this invention to provide a new and improved apparatus for operating on sheet material and which includes an unloader assembly which automatically removes a sheet of material from a machine upon completion of work operations on the sheet by the machine.

Another object of this invention is to provide a new and improved apparatus for operating on sheets of material including a machine having an assembly for moving a sheet along first and second axes relative to a work area and for moving the sheet to an unloading location where it is engaged by an unloader which transfers it from the machine to a pile at a receiving location, and wherein interconnected machine and unloader controls automatically initiate operation of the unloader to transfer the sheet of material from the machine in response to movement of the sheet to the unloading location.

Another object of this invention is to provide a new and improved apparatus for operating on sheets of material wherein the apparatus includes a machine which performs work operations on the sheets of material, an unloader which pulls the sheets of material from the machine, and a detector assembly for detecting when a trailing end portion of a sheet of material is removed from the machine by the unloader.

Another object of this invention is to provide a new and improved apparatus for operating on sheets of material and which includes a machine for performing work operations on each of the sheets in turn, an unloader for engaging a leading end portion of a sheet and removing the sheet from the machine, and a control apparatus for controlling the operation of the unloader,

wherein the control apparatus includes a detector for detecting when a trailing end portion of the sheet has been moved to a predetermined position by operation of the unloader and means for effecting a depositing of the sheet at a receiving location by the unloader in response to the detection of the trailing end portion of the sheet by the detector.

Another object of this invention is to provide a new and improved apparatus for operating on sheets of material and which includes a machine for performing work operations on each of the sheets in turn and an unloader which removes each of the sheets in turn from the machine and deposits them in a pile, and wherein a control assembly lowers the pile when it extends above a predetermined height to prevent interference between the pile and the unloader.

These and other objects and features of the invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a schematic illustration depicting the rela tionship between a punch press and unloader assembly constructed in accordance with the present invention;

FIG. 2 is a partially broken away elevational view, taken generally along the line 2-2 of FIG. 1, depicting the relationship between an unloader trolley, an open clamp assembly mounted on the trolley, and a pile support assembly;

FIG. 3 is a fragmentary elevational view taken generally along the line 3-3 of FIG. 2, further illustrating the relationship between the trolley and open clamp assembly;

FIG. 4 is a fragmentary elevational view illustrating the clamp assembly in a closed condition in which it grips the leading end portion of a sheet to be pulled from the punch press;

FIG. 5 is a partially broken away elevational view, generally similar to FIG. 2, depicting the relationship between the trolley and pile support assembly after a sheet of material has been pulled from the punch press;

FIG. 6 is a fragmentary elevational view illustrating the clamp assembly in the open condition after a sheet has been pulled from the punch press;

FIG. 7 is a fragmentary elevational view, generally similar to FIG. 6, illustrating the disengaging of a sheet from the open clamp assembly by operation of an ejector assembly;

FIG. 8 is a schematic illustration of hydraulic control circuitry for operating a motor to drive the unloader trolley toward and away from the punch press;

FIG. 9 is a schematic illustration of pneumatic control circuitry for operating the clamp and ejector assemblies; and

FIG. 10 is a schematic illustration of electrical control circuitry for controlling operation of the unloader assembly.

An unloader assembly 10 constructed in accordance with the present invention is illustrated in FIGS. 1 and 2 in association with a tape controlled punch press 12 of a known construction. A control assembly 14 for controlling the operation of both the punch press 12 and unloader assembly 10 is illustrated schematically in FIG. 1. The control assembly 14 includes a known reader 16 which effects operation of the punch press 12 and unloader assembly 10 in accordance with a program punched in a tape 18. Although the unloader assembly 10 and control assembly 14 are shown herein in association with a turret type punch press 12, it should be understood that the unloader and control assemblies could be associated with many different types of machines.

The punch press 12 includes a plurality of workholders 22 which grippingly engage a piece of sheet metal 24 which is supported on a work table 26. The workholders 22 are of a known pneumatically actuated type and are mounted on a cross slide 30. The cross slide 30 is movable back and forth along ways 32 to position the sheet 24 along a first or X axis relative to a turret 34 which holds a plurality of tools for punching holes in the sheet. The cross slide 30 and table 26 are movable along cross ways 38 and 40 to position the sheet 24 along a second or Y axis relative to the turret 34. Movement of the sheet 24 by the cross slide 30 and table 26 is effected by machine control apparatus 44 and tape reader 16 in accordance with a program punched into the tape 18. In addition, the control apparatus 44 indexes the turret 34 to work on the sheet 24 with tools selected in accordance with the program punched into the tape 18. Once work operations have been completed on the sheet 24, the tape reader 16 signals the control apparatus 44 to effect operation of the table 26 and cross slide 30 to move the sheet to an unloading location. Since the operation of tape controlled turret punch presses and similar machines is wellknown, a further description of the specific operation of the punch press 12 will not be included herein to avoid prolixity of description.

Upon completion of punching operations and movement of the sheet 24 to the unloading location, the unloader assembly It) removes the sheet from the press and deposits it on a pile 48 which is disposed on a support assembly 50 (see FIG. 2). To move a sheet 24 from the punch press 12 to the pile 48, a clamp assembly 52 grips a leading end portion 54 (see FIG. 4) of the sheet. The sheet 24 is then pulled from the punch press 12 by moving a trolley 56, on which the clamp assembly 52 is mounted, away from the punch press until a trailing end portion 58 of the sheet clears an end of sheet detector assembly 60 (FIG. and falls onto the pile 48. The clamp assembly 52 is then opened (FIG. 6)'and an ejector assembly 62 is operated to push the leading end portion 54 of the sheet 24 out of the clamp assembly 52 onto the pile 48 (FIG. 7). After the sheet 24 has been deposited on the pile 48, the ejector assembly 62 is retracted and the trolley 56 is ready to move the clamp assembly 52 back to the loading position of FIG. 2 to engage the next succeeding sheet after it has been operated on by the punch press 12.

To minimize the time required to process each sheet of material, it is important that the unloader assembly remove a completed sheet from the punch press as soon as possible so that punching operations on a next succeeding sheet can be undertaken. To this end, the control assembly 14 automatically initiates operation of the unloader 10 to remove a sheet from the punch press 12 as soon as the punch press has completed operations on the sheet and moved it to the unloading location. Thus, upon completion of a punching cycle by the press 12, the tape 18 is indexed by the reader 16 and a signal is transmitted to the machine control apparatus 44 to effect operation of the carriage 30 to move the sheet 24 to the unloading location in which the leading end portion 54 of the sheet extends into the unloader 10 in the manner illustrated in FIG. 2. In response to movement of the sheet to the unloading location, the tape reader 16 is indexed and thereafter transmits a signal to an unloader control apparatus 64 to initiate movement of the trolley 56 to the loading position shown in FIG. 2.

The control apparatus 64 is connected over a path indicated schematically at 68 in FIG. 1 with a reversible hydraulic motor 70 mounted on the trolley 56. The reversible motor 70 is operable to drive the trolley 56 between an unloading position (shown in dashed lines in FIG. 1) and a loading position (shown in solid lines in FIGS. 1 and 2). To effect forward operation of the motor 70, the control apparatus includes a solenoid 74 (FIG. 8) which is energized to operate a control valve in hydraulic circuitry 78 to port fluid from a pump 82 through conduits 84 and 86 to the hydraulic motor 70. The hydraulic motor 70 is connected with drain 88 by the actuated valve 80 and conduits 90 and 92.

The high pressure fluid operates the motor 70 in a forward direction to move the trolley 56 to the loading position (FIG. 2). To this end, forward operation of the motor 70 rotates a pinion gear 96 in a clockwise or forward direction along a rack 98. The cooperation between the pinion and rack gears 96 and 98 moves the trolley 56 along a pair of parallel spaced apart support rails or tracks 100 and 102 (see FIG. 1) toward the loading position. When the trolley 56 reaches the loading position, a cam 102 (FIG. 2) on the trolley 56 actuates a load position limit switch 104 to de-energize the solenoid 74 (FIG. 8) and return the valve 80 to its normal position to thereby interrupt operation of the hydraulic motor 70.

The clamp assembly 52 is then operated from the open condition of FIG. 2 to the closed condition of FIG. 4 to grip the leading end portion 54 of the sheet 24. Accordingly, the unloader control apparatus 64 is connected with the clamp assembly 52 by control circuitry indicated schematically at 108 in FIG. 1. The control apparatus 64 includes a valve 110 (FIG. 9) which is operated by energizing a solenoid ll2,'to port air from a source 114 to piston and cylinder assemblies 116 and 118 (see FIGS. 1 and 3) through conduits 120 and 122 (FIG. 9). The opposite ends of the piston and cylinder assemblies 116 and 118 are ported to atmosphere by the actuated valve l10 through conduits 124 and 126. The high pressure air extends the piston and cylinders 116 and 118 to grip the leading end portion 54 of a sheet 24 between upper and lower clamp members and 132 (see FIG. 4).

Contemporaneously with the gripping of the leading end portion 54 on the sheet 24 by the clamp assembly 52, the workholders 22 are pneumatically actuated to an open condition to release the sheet 24. Thus, the sheet 24 is released by the punch press 12 immediately after it is securely gripped by the clamp assembly 52 in the unloader 10. The sheet 24 can now be pulled from the punch press 12 by moving the trolley 56 away from the punch press from the loading position shown in FIG. 2 to the unloading position shown in FIG. 5.

To insure that an unloading operation is not started before the punch press 12 has completely released the sheet 24, the trolley 56 is not moved away from the punch press 12 until after the machine control apparatus 44 signals that the sheet 24 has been released by the workholders 22. This signal is provided by a pressure switch (see line 9 of FIG. 10) which is exposed to fluid pressure in a conduit 142 through which air is conducted to effect operation of the pneumatically actuated workholders 22. Upon opening of the workholders to release the sheet 24, the pressure switch 140 is actuated to transmit a signal to the tape reader 16 to index the tape 18. A signal is then transmitted from the reader 16 to the unloader control apparatus 64 to effect energization of a solenoid 144 (FIG. 8). Energization of the solenoid 144 operates the valve 80 to drive the motor 70 in the reverse direction. To accomplish this, the actuated valve 80 ports high pressure fluid from the pump 82 to the conduit 90 while connecting the conduit 86 influid communication with drain 88.

As the motor 70 drives the trolley 56 away from the punch press 12, the sheet 24 will be pulled out of the punch press and into the unloader 10. Once the sheet 24 has been pulled completely into the unloader 10, the trailing end portion 58 of the sheet moves past the end of sheet detector assembly 60 and drops onto the pile 48. As the trailing end portion 58 of the sheet 24 moves past the end of sheet detector assembly 60, a switch actuator arm 148 in the detector assembly 60 is released and a detector switch 150 opens to provide a signal to the unloader control apparatus 64 (FIG. 1) over path 152 indicating that the sheet 24 has been pulled from the punch press 12. In response to the signal from the end of sheet detector assembly 60, the control apparatus 64 stops the motor 70 by deenergizing the solenoid 144 (FIG. 8) to return the valve 80 to its neutral position. This interrupts operation of the motor 70 with the trailing end 58 of the sheet in substantially the position shown in FIG. 5. Although the detector assembly 60 is illustrated as merely including a known type of pressure switch 150, it is contemplated that an end of the sheet detector assembly similar to that disclosed and claimed in copending application Ser. No. 133,873, filed by Earl D. Harris on Apr. 14, 1971 now Pat. No. 3,722,880 issued on Mar. '27, 1973 and entitled Detector Assembly could be utilized.

Once the trailing end portion 58 of the sheet 24 moves onto the pile 48 (FIG. 5), the leading end portion 54 of the sheet is disengaged from the clamp assembly 52 and deposited on the pile 48. Thus, after actuation of the detector assembly 60 and the passage of sufficient time to enable the trolley 56 to stop, the solenoid 1 12 is de-energized to operate the valve 110 to the normal or neutral position shown in FIG. 9. This connects the rod ends of the clamp cylinders 116 and 118 with air under pressure to operate the clamp assembly 52 from the closed position of FIG. 5 to the open position of FIG. 6. Immediately after the clamp assembly 52 is opened, the leading end 54 of the sheet 24, is moved out from between the clamp members 130 and 132. This is accomplished by operating the ejector assembly 62 from the retracted condition of FIG. 6 to the extended condition of FIG. 7. As the ejector assembly 62 is extended, the leading end portion 54 of the sheet 24 is pushed out of the clamp assembly 52.

To provide for this cooperation between the clamp assembly 52 and ejector assembly '62, operation of the clamp assembly toward the opened condition of FIG. 6 results in a clamp open limit switch 162 being closed by an arm 164 as the piston and cylinder assembly 118 is retracted (see FIGS. 5 and 6). Actuation of the clamp open limit switch 162 completes a circuit in the unloader control apparatus 64 (FIG. 1) to activate the ejector assembly 62 over a path indicated schematically at 168 in FIG. 1. To this end, pneumatic circuitry for operating the ejector assembly 62 includes a plurality of conduits 170 and 172 which connect a piston and cylinder assembly 174 in communication with a control valve 176. The control valve 176 is operated by energizing a solenoid 178 in response to a closing of the clamp open limit switch 162 to connect air under pressure from the supply 114 with the head end of the ejector cylinder 174. Of course, this effects operation of the ejector assembly 62.from the retracted or normal condition of FIG. 6 to the extended or operated condition of FIG. 7. As the ejector assembly 62 is extended, a pusher member 184 pushes the trailing end portion 54 of the sheet 24 out of the clamp assembly 52 (see FIG. 7) to thereby deposit the sheet 24 on the pile 48.

Once the sheet 24 has been pushed from the clamp assembly 52, the ejector assembly 62 is retracted so that the unloader 10 is ready for the next succeeding cycle of operation. To this end, movement of the pusher member 184 to the forward or extended position actuates a slide forward limit switch 188 to effect de-energization of the solenoid 178. De-energization of the solenoid 178 returns thecontrol valve 176 to its normal or neutral position (FIG. 9) and air under pressure is conducted to the rod end of the cylinder 174 to retract the ejector assembly 158.

After the sheet 24 has been ejected from the clamp assembly 52 and the ejector assembly 62 retracted, the trolley 56 is ready to move to the unloading position of FIG. 2 to pull the next succeeding sheet of material from the punch press 12. While the trolley remains in the unloading position of FIG. 5 until completion of the operating cycle of a punch press 12 on the next succeeding sheet, it should be understood that the trolley 56 could, if desired, be moved to the loading position of FIG. 2 to await the completion of the punching of the next sheet.

In moving from the unloading position of FIG. 5 to the loading position of FIG. 2, the trolley passes over the pile 48 of sheets. As the sheets accumulate on the pile 48, they will eventually reach a height such that the uppermost sheet in the pile would interfere with movement of the trolley 56 from the unloading position to the loading position. To prevent interference between the pile of sheets 48 and trolley 56 as the trolley passes over the pile, a pile height detector 192 is mounted on the trolley 56 to effect actuation of a drive mechanism 196 to lower a pile support table 198 when the uppermost sheet on the pile 48 is above a predetermined height.

Accordingly, when the trolley 56 is moved from the unloading position (FIG. 5) to the loading position (FIG. 2), a downwardly projecting feeler member or whisker 202 engages the uppermost sheet in the pile 48 to actuate a detector switch 204 in the pile height detector 192 if the pile extends upwardly for a sufficient distance. Closing of the switch 192 transmits a signal over a control path, indicated schematically at 206 in FIG. 1, to activate a table positioning motor 208 (FIG. 10) in the drive mechanism 196 (FIG. 2) to lower the support table 198. As the support table 198 is lowered, the uppermost sheet is moved away from the feeler or detector member 202 so that the switch 204 is again opened to de-energize the motor 208. Thus, the detector 192 activates the motor 208 to lower the table 198 approximately one sheet'thickness each time the trolley 56 is moved from the unloading position of FIG. 5 to the loading position of :FIG. 2.

As the sheets 24 accumulate on the pile 48 during continued operation of the punch press 12, the support table 198 will be lowered further and further. Eventually, a table down limit switch 210 (FIG. 2) will be closed by an actuator 212. Closing the table down limit switch 210 energizes a warning light 214 (FIG. 10, line 16) to indicate to an operator that the pile 48 should be removed from the unloader 10. Once the pile of sheets has been removed from the unloader 10, a push button 216 (FIG. 10, line 14) is actuated to operate the reversible motor 208 to raise the table 198 to its uppermost position.

The trolley 56 includes a plurality of support wheels or rollers 220 which are mounted on frame members 222 and 224 (see FIGS. 1 and 2). The rollers 220 engage opposite sides of horizontally extending flanges 226 of the support rails 100 and 102 to prevent vertical movement of the trolley. The hydraulic drive motor 70 is mounted on the trolley 56 so that the pinion gear 96 is maintained in engagement with the rack 98 as the trolley moves along the tracks 100 and 102. The clamp assembly 52 is connected with a pair of support members 230 and 232 (see FIG. 3) which extend between vertically extending side members 234 and 236. The ejector assembly 62 is mounted on a support platform 240 which is connected with the members 222 and 224 by a pair of downwardly extending side plates 242. Thus, the ejector assembly 62 and clamp assembly 52 are mounted on and move with the trolley 56 above the pile 48 as the trolley moves from the loading position of FIG. 2 to the unloading position of FIG. 5. A trolley stop limit switch 250 (FIG. 2) is advantageously mounted at the end of the tracks 100 and 102 to interrupt movement of the trolley 56 and prevent it from running off the tracks if for some reason the controls for stopping the trolley at the end of the pile 48 malfunction.

The unloader control apparatus 64 of FIG. 1 includes the electrical control circuitry 260 of FIG. as well as the hydraulic and pneumatic control circuitry of FIGS. 8 and 9. As soon as a cycle of operation of the punch press 12 is completed, the tape reader 16 indexes the tape 18 and transmits a start signal to the circuitry 260 over a lead 262 (see FIG. 10, line 2). This start signal immediately initiates operation of the unloader 10 to remove the sheet 24 from the punch press 12 by energizing the initiate cycle relay ICR (FIG. 10, line 3) which is then held up over a circuit including its own normally open contacts ICR-l.

Upon initiation of an unloading cycle by energization of the [CR relay, the trolley 56 moves from the unloading position of FIG. 5 to the loading position of FIG. 2. Accordingly, when the solenoid 74 (FIG. 10, line 6) is energized by a closing of the ICR-2 contacts, the control valve 80 (FIG. 8) is operated. This starts the trolley drive motor 70 operating in a forward direction to move the trolley 56 from the unloading position of FIG. 5 to the loading position of FIG. 2. When the trolley 56 reaches the loading position, normally closed contacts 266 (FIG. 10, line 3) in the load position limit switch 104 are opened to de-energize the ICR relay and the solenoid 74 to interrupt operation of the trolley drive motor 70.

Once the trolley 56 has been moved to the loading position, the clamp assembly 52 is closed on the leading end portion 54 of the sheet 24. Accordingly, actuation of the load position limit switch 104 also closes normally open switch contacts 268 (FIG. 10, line 4) to energize timer ITR. At the end of a relatively short time period during which the trolley 56 is brought to a complete stop, the timer ITR closes normally open contacts ITR-1 (FIG. 10, line 7) to energize the clamp solenoid 112. Energizing clamp solenoid 112 effects operation of the control valve (see FIG. 9) to operate the clamp assembly 52 from the open condition of FIG. 2 to the closed position of FIG. 4.

After the clamp assembly 52 has gripped the leading end portion 54 on the sheet 24, the workholders 22 are released and a pressure switch activates the tape reader 16 (FIG. 10, line 9) to provide a signal to momentarily energize a 2TR relay. The 2TR relay is held energized over its own normally open contacts 2TR-1 and the end of sheet detector switch (FIG. 10, line 8) which is now held closed by the pressure of the leading end portion of the sheet 54 against the arm 148. Energization of the 2TR relay closes the normally open contacts 2TR-2 (FIG. 10, line 10) to energize the solenoid 144. As was previously explained, energizing the solenoid 144 operates the trolley drive motor control valve 80 (FIG. 8) to initiate movement of the trolley 56 toward the unloading position of FIG. 5.

As the sheet 24 is pulled from the punch press 12, the trailing end portion 58 of the sheet will eventually move out of the punch press and past the end of sheet detector assembly 60. When this occurs, the end of the sheet detector switch 150 is opened to effect a deenergization of the 2TR (FIG. 10, line 8) relay. Of course, de-energization of the 2TR relay opens the normally open contacts 2TR-2 (FIG. 10, line 10) to thereby de-energize the solenoid 144 and interrupt operation of the trolley drive motor 70. If for some unforeseen reason the operation of the motor 70 is not interrupted in response to opening of the detector switch 150, the trolley stop limit switch 250 (FIG. 10, line 19) will be closed to energize the TS relay and open contacts TS-l (FIG. 10, line 8) to stop the trolley 56.

The clamp solenoid 112 (FIG. 10, line 7) is then deenergized to effect operation of the clamp assembly 52 to the open condition of FIG. 6. This is accomplished when the 2TR relay is de-energized since the 2TR-3 contacts (FIG. 10, line 5) will open to de-energize the lTR timer (FIG. 10, line 4) so that timer contacts ITR-1 open. It should be noted that the load position limit switch contacts 268 (FIG. 10, line 4) are now open since the trolley 56 has moved away from the loading position of FIG. 2.

When the clamp assembly 52 reaches the open condition of FIG. 6, the clamp open limit switch 162 is closed to energize the ejector solenoid 178 (FIG. 10, line 11). This operates the valve 176 (FIG. 9) to extend the ejector assembly 62 so that the leading end portion 54 of the sheet 24 is pushed out of the clamp assembly 52 (FIG. 7). When the pusher member 184 reaches the fully extended position of FIG. 7, the slide forward limit switch 188 (FIG. 10, line 12) is closed to energize the 2CR relay. Energizing the 2CR relay opens its normally closed contacts 2CR-2 (FIG. 10, line 11) to deenergize the ejector solenoid 178 so that the ejector assembly 62 is retracted. The 2CR relay is then maintained in an energized condition over its own normally open contacts 2CR-1.

After the punch press 12 has completed operations on the next succeeding sheet, the sheet will be moved to the unloading location (see FIG. 2) and a signal will be transmitted over the lead 262 (FIG. 10, line 2) to automatically initiate the next cycle of operation of the unloader assembly 10. Upon initiation of this unloading cycle, the trolley 56 moves toward the loading position of FIG. 2 and the pile height detector 194 is moved across the pile 48. Since a sheet was added to thepile during the last loading cycle, the detector or feeler member 202 will engage the uppermost sheet and close the pile height detector switch 204 (FIG. 10, line 15). Closing the detector switch 204 energizes motor relay 2M (FIG. 10, line 15) to close its normally open contacts 2M and effect energization of the support table motor 208 to lower the support table 198. As the table 198 is lowered, the uppermost sheet on the pile 48 moves out of engagement with the feeler member 202 and the pile height detector switch 204 opens to deenergize the 2M relayand interrupt operation of the motor 208.

As the sheets collect on the pile support table 198, the table will gradually be lowered until the table down limit switch 210 (FIG. 10, line 16) is closed. Closing the table down limit switch 2l0 willenergize the indicator light 214 to warn an operator of the unloader assembly 10 that the pile 48should be removed from the support table 198. Of course, suitable interlock contacts could be associated with the table down limit switch 210 to prevent initiation of thenext succeeding cycle of operation of the unloader assembly 10. After the pile 48 hasbeen removed from the support table 198, a push button switch 216 is closed to energize the relay 1M and close its normally open contacts so that the motor 208 raises the'table 198 to a position to receive sheets on successive cycles of operation of the unloader assembly 10.

During operation of the motor assembly 10, the pump 82 is continuously driven by a motor 274 (FIG. 8). When the unloader assembly 10 is to be initially started, a push button switch 278 (line 17, FIG. 10) is closedte energize a relay 3M to close the. normally open 3M contacts to thereby energize the pump motor 274. The 3M relay is maintained energized during the operation of the unloader 10 over its own normally open contacts 3M-1. When the unloader assembly 10 is to be stopped, a push button 208 is actuated to deenergize the 3M relay and the pump drive motor 274.

In view of the foregoing description, it is apparent that an improved apparatus for operating on sheets of material includes a punchpress 12 or other machine and an unloader assembly 10. Upon completion of work operations on a sheet 24, a common control assembly 14 for the punch press 12 and unloader l automatically initiatesoperation of the unloader to minimize the amount of time required to process each of the sheets 24. The unloader includes a clamp assembly 52 which is mounted on a trolley 56. Once the leading end portion of a sheet has been gripped by the clamp assembly 52, the trolley 56 is moved along a path extending over the pile 48 to pull the sheet from the punch press 12. When a trailing end portion 58 of the sheet 24 has cleared the punch press 12, an end of sheet detector assembly 60 is actuated to stop the movement of the trolley and initiate operation of the clamp assembly 52 to the open condition of FIG. 6. The ejector assembly 62 is then extended to push the leading end portion54 of the sheet 24 out of the clamp assembly.

On the next succeeding cycle of operation of the unloader 10, the trolley 56 is moved back over the pile 48 to the loading position of FIG. 2. As the trolley moves over the pile 48, a pile height detector l92is actuated if the uppermost sheet on the pile 48 is above a predetermined height. Assuming that this is the case, actuation of the detector 192 effects the operation of a drive assembly 196 to lower the table by' approxirnately one sheet thickness, that is until the sheet detector 192 is no longer actuated by the uppermost sheet on the pile 48. Accordingly, each time a sheet is deposited on the pile 48, the pile is lowered by approximately one sheet thickness on the next cycle of operation of the unloader assembly 10 to thereby prevent interference between the pile 48 and the trolley 56 as the trolley 56 moves back and forth across the pile.

Although the unloader 10 and controls 14 have been illustrated herein in association with a punch press 12, it should be understood that they could be associated with other types of machines which operate on sheet material. It also should be understood that although specific preferred embodiments of the trolley, clamp, and ejector assemblies have been described herein, these assemblies could be constructed in a somewhat different manner if desired.

Having described a specific preferred embodiment of the invention, the following is claimed:

1. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of thesheets of material in turn, unloader means for engaging a leading end portion of a sheet of material and moving the sheet of material from said machine to a receiving location, said unloader means including a trolley assembly which is mounted for reciprocating movement toward and away from said machine, clamp. means operable between open and closed conditions and mounted on said trolley assembly for grippingly engaging the leading end portion ofa sheet of material, drive means for moving said trolley assembly away from said machine to pull a sheet of material gripped by said clamp means from said machine to the receiving location, and pusher means for pushing the leading end portion of the sheet material out of said clamp means when said clamp means is in the open condition, and control means for controlling the operation of said unloader means, said control means including detector'means for detecting when a trailing end portion of the sheet of material has been moved to a predetermined position by operation of said unloader means and means for effecting a depositing of the sheet material at the receiving location by said unloader means in response to detection of the trailing end portion of the sheet of material at the predetermined position by said detector means, said detector means being operable to interrupt movement of said trolley in response to the detection of the trailing end portion of a sheet of material at the predetermined position, said means for effecting a depositing of the sheet material at the receiving location including means for effecting operation of said clamp means to an open condition to release the leading end portion of the sheet of material in response to detection of the trailing end portion of the sheet material at the predetermined position by said detector means and means for effecting operation of said pusher means in response to opening of said clamp means.

2. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of the sheets of material in turn, unloader means for engaging a leading end portion of a sheet of material and moving the sheet of material from said machine to a receiving location, and control means for controlling the operation of said unloader means, said control means including detector means for detecting when a trailing end portion of the sheet of material has been moved to a predetermined position by operation of said unloader means and means for effecting a depositing of the sheet of material at the receiving location by said unloader means in response to detection of the trailing end portion of the sheet of material at the predetermined position by said detector means, said unloader means including a trolley assembly which is mounted for reciprocating movement toward and away from said machine, clamp means mounted on said trolley assembly for grippingly engaging the leading end portion ofa sheet of material, drive means for moving said trolley assembly away from said machine to pull a sheet of material gripped by said clamp means from said machine to the receiving location, movable support surface means at the receiving location for supporting a pile of the sheets of material, and drive means for raising and lowering said support surface means, said detector means being operable to interrupt movement of said trolley in response to the detection of the trailing end portion of a sheet of material at the predetermined position, said control means including means mounted on said trolley assembly for detecting when the uppermost sheet on the pile of sheets is above a predetermined level and for initiating operation of said drive means to lower said support surface in response to detection that the uppermost sheet is above the predetermined level.

3. Apparatus as set forth in claim 2 wherein said means for detecting when the uppermost sheet on the pile of sheets is above a predetermined level includes a movable feeler element which extends downwardly from said trolley assembly to the predetermined level and is movable from a first position to a second position by engagement with the pile of sheets during'movement of said trolley assembly toward said machine when the uppermost sheet on the pile of sheets is above the predetermined level.

4. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of the sheets of material in turn, said machine including means for moving each of the sheets of material in turn to an unloading location upon completion of work operations on the sheet, unloader means for moving each of the sheets of material in turn from said unloading location, said unloader means including a clamp assembly operable from an open condition to a closed condition to grip a leading end portion of a sheet of material at the unloading location, first actuator means for operating said clamp assembly between the open and closed conditions, second actuator means for effecting relative movement between the trailing end portion of the sheet of material and said clamp assembly when said clamp assembly is in the open condition to disengage the trailing end portion of the sheet of material from said clamp assembly, and motor means for moving said clamp assembly toward and away from said machine, said apparatus further including control means for controlling operation of said unloader means, said control means including means for effecting operation of said first actuator means to operate said clamp assembly to the closed condition to grip a sheet of material at the unloading location, for thereafter effecting operation of said motor means to move said clamp assembly away from said machine through a distance which is at least substantially as great as the length of the gripped sheet of material to pull the gripped sheet of material from said machine to a pile at the receiving location, and for effecting operation of said first actuator means to operate said clamp assembly to the open condition to release the sheet of material after a trailing end portion of the sheet of material has been pulled from said machine, said control means further including means for effecting operation of said second actuator means to disengage the sheet of material from said clamp assembly upon operation of said clamp assembly to the open condition.

5. Apparatus as set forth in claim 4 wherein said second actuator means includes pusher means for pushing the leading end portion of the sheet of material out of said clamp assembly.

6. Apparatus as set forth in claim 4 wherein said control means includes detector means for detecting when a sheet of material is removed from said machine by said unloader means.

7. Apparatus as set forth in claim 4 wherein said unloader means includes a movable support surface for supporting a pile of the sheets of material and drive means for raising and lowering said support surface, said control means including detector means for detecting when the uppermost sheet of material on the pile is above a predetermined level and means for effecting operation of said drive means to lower said support surface in response to detection by said detector means that the uppermost sheet of material on the pile is above the predetermined level.

8. Apparatus as set forth in claim 4 wherein said control means further includes detector means for detecting movement of the trailing end portion of the sheet of material to a predetermined position relative to the receiving location and means for effecting operation of said actuator means to deposit the sheet of material on the pile at the receiving location by said unloader means in response to detection of the trailing end por tion of the sheet of material by said detector means.

9. Apparatus as set forth in claim 8 wherein said unloader means includes a movable pile support means at the receiving location for supporting the pile of sheets, drive means for raising and lowering said pile support means, said control means including means for effecting operation of said drive means to lower said pile support means in response to the pile obtaining a predetermined height.

10. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of the sheets of material in turn, unloader means for moving each of the sheets of material in turn from said machine to a receiving location, said unloader means including a trolley assembly which is mounted for reciprocating movement toward and away from said machine along a predetermined path which is at least partially disposed above the receiving location, clamp means mounted on said trolley assembly for grippingly engaging a leading end portion ofa sheet of material, and motor means for moving said trolley assembly and clamp means toward and away from said machine along the predetermined path to pull each of the sheets of material in turn from said machine to the receiving location, movable surface means disposed at the receiving location below the predetermined path for supporting a pile of sheets at the receiving location, drive means for lowering said surface means and the pile of sheets supported thereon, and control means for controlling the operation of said unloader means, said control means including detector means mounted on said trolley assembly for movement therewith across the pile of sheets for detecting when the pile of sheets extends to a level above a predetermined level and means for initiating operation of said drive means to lower said surface means and the pile of sheets thereon in response to detection by said detector means that the pile of sheets extends to a level above the predetermined level.

11. Apparatus as set forth in claim wherein said control means includes means for detecting when said trolley assembly has moved along the predetermined path through a first distance which is at least sufficient to pull a sheet of material from said machine to the receiving location and for interrupting operation of said motor means in response to a detecting that said trolley assembly has moved along the predetermined path through the first distance.

12. Apparatus as set forth in claim 11 wherein said unloader means includes means for operating said clamp means to an open condition in response to a detecting that said trolley assembly has moved along the predetermined path through the first distance.

13. Apparatus as set forth in claim 12 wherein said control means further includes means for automatically effecting operation of said motor means to'move said trolley assembly along the predetermined path to a position adjacent to the leading end portion of a sheet of material upon completion of work operations on the sheet of material by said machine. 

1. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of the sheets of material in turn, unloader means for engaging a leading end portion of a sheet of material and moving the sheet of material from said machine to a receiving location, said unloader means including a trolley assembly which is mounted for reciprocating movement toward and away from said machine, clamp means operable between open and closed conditions and mounted on said trolley assembly for grippingly engaging the leading end portion of a sheet of material, drive means for moving said trolley assembly away from said machine to pull a sheet of material gripped by said clamp means from said machine to the receiving location, and pusher means for pushing the leading end portion of the sheet material out of said clamp means when said clamp means is in the open condition, and control means for controlling the operation of said unloader means, said control means including detector means for detecting when a trailing end portion of the sheet of material has been moved to a predetermined position by operation of said unloader means and means for effecting a depositing of the sheet material at the receiving location by said unloader means in response to detection of the trailing end portion of the sheet of material at the predetermined position by said detector means, said detector means being operable to interrupt movement of said trolley in response to the detection of the trailing end portion of a sheet of material at the predetermined position, said means for effecting a depositing of the shEet material at the receiving location including means for effecting operation of said clamp means to an open condition to release the leading end portion of the sheet of material in response to detection of the trailing end portion of the sheet material at the predetermined position by said detector means and means for effecting operation of said pusher means in response to opening of said clamp means.
 2. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of the sheets of material in turn, unloader means for engaging a leading end portion of a sheet of material and moving the sheet of material from said machine to a receiving location, and control means for controlling the operation of said unloader means, said control means including detector means for detecting when a trailing end portion of the sheet of material has been moved to a predetermined position by operation of said unloader means and means for effecting a depositing of the sheet of material at the receiving location by said unloader means in response to detection of the trailing end portion of the sheet of material at the predetermined position by said detector means, said unloader means including a trolley assembly which is mounted for reciprocating movement toward and away from said machine, clamp means mounted on said trolley assembly for grippingly engaging the leading end portion of a sheet of material, drive means for moving said trolley assembly away from said machine to pull a sheet of material gripped by said clamp means from said machine to the receiving location, movable support surface means at the receiving location for supporting a pile of the sheets of material, and drive means for raising and lowering said support surface means, said detector means being operable to interrupt movement of said trolley in response to the detection of the trailing end portion of a sheet of material at the predetermined position, said control means including means mounted on said trolley assembly for detecting when the uppermost sheet on the pile of sheets is above a predetermined level and for initiating operation of said drive means to lower said support surface in response to detection that the uppermost sheet is above the predetermined level.
 3. Apparatus as set forth in claim 2 wherein said means for detecting when the uppermost sheet on the pile of sheets is above a predetermined level includes a movable feeler element which extends downwardly from said trolley assembly to the predetermined level and is movable from a first position to a second position by engagement with the pile of sheets during movement of said trolley assembly toward said machine when the uppermost sheet on the pile of sheets is above the predetermined level.
 4. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of the sheets of material in turn, said machine including means for moving each of the sheets of material in turn to an unloading location upon completion of work operations on the sheet, unloader means for moving each of the sheets of material in turn from said unloading location, said unloader means including a clamp assembly operable from an open condition to a closed condition to grip a leading end portion of a sheet of material at the unloading location, first actuator means for operating said clamp assembly between the open and closed conditions, second actuator means for effecting relative movement between the trailing end portion of the sheet of material and said clamp assembly when said clamp assembly is in the open condition to disengage the trailing end portion of the sheet of material from said clamp assembly, and motor means for moving said clamp assembly toward and away from said machine, said apparatus further including control means for controlling operation of said unloader means, said control means including means for effecting operation of said first actuator means to operate said clamp assembly to the closed condition to grip a sheet of material at the unloading location, for thereafter effecting operation of said motor means to move said clamp assembly away from said machine through a distance which is at least substantially as great as the length of the gripped sheet of material to pull the gripped sheet of material from said machine to a pile at the receiving location, and for effecting operation of said first actuator means to operate said clamp assembly to the open condition to release the sheet of material after a trailing end portion of the sheet of material has been pulled from said machine, said control means further including means for effecting operation of said second actuator means to disengage the sheet of material from said clamp assembly upon operation of said clamp assembly to the open condition.
 5. Apparatus as set forth in claim 4 wherein said second actuator means includes pusher means for pushing the leading end portion of the sheet of material out of said clamp assembly.
 6. Apparatus as set forth in claim 4 wherein said control means includes detector means for detecting when a sheet of material is removed from said machine by said unloader means.
 7. Apparatus as set forth in claim 4 wherein said unloader means includes a movable support surface for supporting a pile of the sheets of material and drive means for raising and lowering said support surface, said control means including detector means for detecting when the uppermost sheet of material on the pile is above a predetermined level and means for effecting operation of said drive means to lower said support surface in response to detection by said detector means that the uppermost sheet of material on the pile is above the predetermined level.
 8. Apparatus as set forth in claim 4 wherein said control means further includes detector means for detecting movement of the trailing end portion of the sheet of material to a predetermined position relative to the receiving location and means for effecting operation of said actuator means to deposit the sheet of material on the pile at the receiving location by said unloader means in response to detection of the trailing end portion of the sheet of material by said detector means.
 9. Apparatus as set forth in claim 8 wherein said unloader means includes a movable pile support means at the receiving location for supporting the pile of sheets, drive means for raising and lowering said pile support means, said control means including means for effecting operation of said drive means to lower said pile support means in response to the pile obtaining a predetermined height.
 10. An apparatus for operating on sheets of material, said apparatus comprising a machine for performing work operations on each of the sheets of material in turn, unloader means for moving each of the sheets of material in turn from said machine to a receiving location, said unloader means including a trolley assembly which is mounted for reciprocating movement toward and away from said machine along a predetermined path which is at least partially disposed above the receiving location, clamp means mounted on said trolley assembly for grippingly engaging a leading end portion of a sheet of material, and motor means for moving said trolley assembly and clamp means toward and away from said machine along the predetermined path to pull each of the sheets of material in turn from said machine to the receiving location, movable surface means disposed at the receiving location below the predetermined path for supporting a pile of sheets at the receiving location, drive means for lowering said surface means and the pile of sheets supported thereon, and control means for controlling the operation of said unloader means, said control means including detector means mounted on said trolley assembly for movement therewith across the pile of sheets for detecting when the pile of sheets extends to a level above a predetermined level and means foR initiating operation of said drive means to lower said surface means and the pile of sheets thereon in response to detection by said detector means that the pile of sheets extends to a level above the predetermined level.
 11. Apparatus as set forth in claim 10 wherein said control means includes means for detecting when said trolley assembly has moved along the predetermined path through a first distance which is at least sufficient to pull a sheet of material from said machine to the receiving location and for interrupting operation of said motor means in response to a detecting that said trolley assembly has moved along the predetermined path through the first distance.
 12. Apparatus as set forth in claim 11 wherein said unloader means includes means for operating said clamp means to an open condition in response to a detecting that said trolley assembly has moved along the predetermined path through the first distance.
 13. Apparatus as set forth in claim 12 wherein said control means further includes means for automatically effecting operation of said motor means to move said trolley assembly along the predetermined path to a position adjacent to the leading end portion of a sheet of material upon completion of work operations on the sheet of material by said machine. 